Methods for iris recognition implement pattern-recognition techniques to compare an acquired image of a subject's iris against a previously stored image of the subject's iris, and thereby determine or verify identity of the subject. A digital feature set corresponding to an acquired iris image is encoded based on the image, using mathematical or statistical algorithms. The digital feature set or template is compared with databases of previously encoded digital templates (stored feature sets corresponding to previously acquired iris images), for locating a match and determining or verifying identity of the subject.
Apparatuses for iris recognition typically comprise an imaging apparatus for capturing an image of the subject's iris(es) and an image processing apparatus for comparing the captured image against previously stored iris image information. The imaging apparatus and image processing apparatus may comprise separate devices, or may be combined within a single device.
Iris based biometric technologies are susceptible to spoofing attacks, in which faked images of an iris are passed off as a genuine iris presented for iris recognition. For example, certain iris-identification systems are susceptible to spoofing by high resolution printed images of a subject's eye or iris being presented to the iris camera for imaging and subsequent feature extraction and comparison.
Previously known methods of iris spoof detection (disclosed in U.S. Pat. No. 8,364,971) include one or more of (a) altering levels of illumination and observing effects of change in illumination intensity on the eye, (b) changing the position or pattern of LEDs providing illumination and observing differences in specular patterns reflected off the cornea of the eye, and (c) modifying an angle of illumination over successive images to change the level of reflectance from within the eye as seen through the pupil, commonly known as “red eye.” Since all of the above involve varying levels of active illumination upon a subject's eye, such methods may result in user discomfort, and also present eye safety concerns in cases where intensity of illumination increases moves towards and beyond safety thresholds.
It is an objective of the present invention to provide safe and effective solutions for spoof detection in iris based biometric systems.